• 멤브레인
• /
• 제19권1호
• /
• pp.63-71
• /
• 2009

본 연구에서는 연료전지용 전해질 복합체용 지지체 막을 저가의 우수한 기계적 열적 안정성을 가지는 Polysulfone으로 상전이 법을 이용하여 제조하였다. 제조된 막을 이용하여 농도변화와 노출시간의 변화에 따른 열 수축율, 통기도, 모폴로지, 기계적 물성 및 다공도를 측정하였다. 모폴로지를 조절하기 위해 공기 중 노출 시간과 고분자 농도가 제어되었으며, 제조된 막은 고분자 농도 변화에 관계없이 모두 스폰지 구조를 나타내었다. 고분자의 농도가 증가함에 따라 기계적 열적 안정성은 증가하였지만, 다공도는 감소하는 결과를 보였다. 실험결과 20 wt%의 PSf 고분자 용액을 사용하여 2분의 노출시간을 두고 제조된 고분자 막에서 연료전지용 복합막으로 사용되기 위한 충분한 다공도(80%)와 기계적(tensile : 1.3 MPa), 열적(MD, TD shrinkgage < 1%) 안정성을 나타내었다.

• 멤브레인
• /
• 제20권1호
• /
• pp.69-75
• /
• 2010

수소투과금속인 tantalum과 세라믹 지지체로 $Y_2O_3$-stabilized $ZrO_2$ (YSZ)를 이용하여 cermet 수소분리막을 제조하였다. Ta/YSZ cermet 분리막은 헬륨분위기에서의 예비소결과 고진공 하에서의 본소결을 통해 제조하였으며, 소결 및 밀봉 과정에서 발생하는 불순물은 연마를 통해 제거 가능하였다. 이렇게 제조된 분리막은 tantalum의 연속상이 잘 발달된 치밀구조를 보였다. 수소 해리를 위해 팔라듐 코팅을 한 Ta/YSZ 분리막을 이용하여 $200{\sim}350^{\circ}C$의 범위에서 수소투과실험을 수행하였다. $300^{\circ}C$에서 분리막에 균열이 형성되었고 Pd 코팅층은 몇 곳이 박리되었다. XRD 결과는 tantalum이 수소와 반응하여 $Ta_2H$가 생성되는 것을 보여주며, $Ta_2H$에 인한 격자 팽창이 분리막의 결함을 초래하였다.

• Applied Biological Chemistry
• /
• 제19권2호
• /
• pp.75-81
• /
• 1976

세균포자의 안정성과 관련하여 DPA-Ca-spore complex의 해리에 영향을 주는 여러 요인중 15%까지의 NaCl 농도에 의해서 이루어 지는 높은 이온 강도의 효과에 대하여 실험하고 다음과 같이 결론을 얻었다. 1) NaCl에 의한 포자 현탁액중의 이온강도의 변화는 포자로 부터 Ca-DPA의 해리를 촉진시켜 주며 이런 현상은 포자의 열 저항성을 감소시키고 따라서 보관중 포자의 안정성이 상당히 저하 되었다. 2) 세포질의 membrane은 포자내에서 Ca-DPA의 안정성을 유지하는데 permeability barrier로써 중요한 역할을 한다.

• Bulletin of the Korean Chemical Society
• /
• 제16권1호
• /
• pp.33-36
• /
• 1995

Macrocyclic ligands have been studied as cation carriers in a supported liquid membrane system. Cd2+ has been transported using nitrogen substituted macrocycles as carriers and several divalent metal ions (M2+=Zn, Co, Ni, Cu, Pb, Mg, Ca, and Sr) have been transported using DBN3O2, DBN2O2and PolyNtnoen as carriers in a supported liquid membrane system. Competitive Cd2+-M2+ transport studies have also been carried out with the same system. Ligand structure, stability constant, membrane solvent and carrier concentration are also important parameters in the transport of metal ions.

• 전기화학회지
• /
• 제19권1호
• /
• pp.9-13
• /
• 2016

Electrospun poly(ether sulfone) (PES) membrane impregnated with Nafion (PES-N) have been developed for high-temperature polymer-electrolyte membrane fuel cell (HT-PEMFC). The PES-N obtains highly thermal stability up to $430^{\circ}C$, which is higher than that of the commercial Nafion 212. The PES-N membrane shows a good proton conductivity of about $10^{-2}S\;cm^{-1}$ in a temperature range from $75^{\circ}C$ to $120^{\circ}C$. The membrane-electrode assembly (MEA) with the PES-N membrane exhibits a current density of $1.697A\;cm^{-2}$ at $75^{\circ}C$, and $0.813A\;cm^{-2}$ at $110^{\circ}C$ when the applied voltage is 0.6 V, whereas the MEA with the Nafion 212 membrane shows the current density of $0.647Acm^{-2}$ at $110^{\circ}C$. The results suggest that the PES-N can be a good candidate for a polymer electrolyte membrane of the HT-PEMFC.

• Corrosion Science and Technology
• /
• 제6권3호
• /
• pp.133-139
• /
• 2007

Nickel powder was coated with aluminum nitrate solution to increase the thermal stability of a porous nickel support and control the nickel content in the Pd-Cu-Ni ternary alloyed membrane. Raw nickel powder and alumina coated nickel powder were uniaxialy pressed by home made press with metal cylindrical mold. Though the used nickel powder prepared by pulsed wire evaporation (PWE) method has a good thermal stability, the porous nickel support was too much sintered and the pores of porous nickel support was plugged at high temperature (over $800^{\circ}C$) making it not suitable for the porous support of a palladium based composite membrane. In order to overcome this problem, the nickel powder was coated by alumina and alumina modified porous nickel support resists up to $1000^{\circ}C$ without pore destruction. Furthermore, the compositions of Pd-Cu-Ni ternary alloy membrane prepared by magnetron sputtering and Cu-reflow could be controlled by not only Cu-reflow temperature but also alumina coating amount. SEM analysis and mercury porosimeter analysis evidenced that the alumina coated on the surface of nickel powder interrupted nickel sintering.

• Composites Research
• /
• 제34권6호
• /
• pp.373-379
• /
• 2021

A series of novel PBI/SrTiO₃ nanocomposite membranes composed of polybenzimidazole (PBI) and strontium titanate (SrTiO₃) with a perovskite structure were fabricated with various concentrations of SrTiO₃ through a solution casting method. Various characterization techniques such as proton nuclear magnetic resonance, thermogravimetric analysis, atomic force microscopy (AFM) and AC impedance spectroscopy were used to investigate the chemical structure, thermal, phosphate absorption and morphological properties, and proton conductivity of the fabricated nanocomposite membranes. The optimized PBI/SrTiO₃-8 polymer nanocomposite membrane containing 8wt% of SrTiO₃ showed a higher proton conductivity of 7.95 × 10^-2 S/cm at 160℃ compared to other nanocomposite membranes. The PBI/SrTiO₃-8 composite membrane also showed higher thermal stability compared to pristine PBI. In addition, the roughness change of the polymer composite membrane was also investigated by AFM. Based on these results, nanocomposite membranes based on perovskite structures are expected to be considered as potential candidates for high-temperature PEM fuel cell applications.

• 한국세라믹학회지
• /
• 제33권1호
• /
• pp.110-118
• /
• 1996

• 한국지반신소재학회논문집
• /
• 제3권2호
• /
• pp.31-38
• /
• 2004

2종류 지오그리드의 장기안정성의 검토되었다. 멤브레인 연신형 지오그리드는 지수함수형 인장거동을, 섬유형 지오그리드는 파단점에 가까울수록 빠른 인장특성 증가를 나타내었다. 섬유형 지오그리드의 경우 가속 크리프 시험을 실시하였지만 멤브레인 연신형 지오그리드의 경우에는 열적특성 때문에 가속 크리프 시험을 실시할 수 없었다. 멤브레인 연신형 지오그리드의 크리프 변형률은 인장시험에 의한 극한변형률보다 훨씬 큰 값을 나타내었으며, 섬유형 지오그리드의 크리프 변형에 의한 감소인자는 멤브레인 연신형 지오그리드에 비해 작은 값을 나타내었다.

• BMB Reports
• /
• 제30권1호
• /
• pp.73-79
• /
• 1997

This study was designed to investigate the effects of dietary garlic powder on cytochrome P450 enzymes and membrane stability in murine hepatocarcinogenesis initiated by diethylnitrosamine (DEN). Male Sprague-Dawley rats received a single intraperitoneal injection of DEN (200 mg/kg body wt) dissolved in saline. After 2 weeks on a basal diet, animals were fed diets containing 0. 0.5. 2.0. or 5.0% garlic powder for 6 weeks, and were subjected to two-thirds partial hepatectomy. The areas of placental glutathione S-transferase (GST-P) positive foci were inhibited in rats fed with garlic diets. GST-P is the most effective marker for DEN-initiated lesions. Hepatic microsomal lipid peroxidation was significantly decreased in rats fed with 2.0 and 5.0% garlic powder diets compared with that observed in the control animals and hepatic microsomal glucose 6-phosphatase (G6Pase) activity was found to increase significantly in rats fed 0.5 and 2.0% garlic powder diets. Thus as little as 0.5% garlic powder has a positive effect on the stability of hepatic microsomal membranes. p-Nitrophenol hydroxylase (PNPH) activity and the level of cytochrome P450 2E1 protein in the hepatic microsomes from rats fed diets containing 2.0 and 5.0% garlic powder were much lower than those of control microsomes. Rats fed 5.0% garlic powder diets exhibited the lowest P450 2E1 activity and protein levels among groups. Pentoxyresorufin O-dealkylase activity and immunoblot (cytochrome P450 2B1) analyses were not different between groups. However, the levels of cytochrome P450 1A1/2 protein in rats fed 0.5 and 2.0% garlic powder were significantly induced compared to controls. These results suggest that 2.0% garlic powder is effective in inhibiting the areas of GST-P positive foci, modulating certain isoforms of cytochrome P450 enzymes and stabilizing the hepatic microsomal membrane. Thus, the selective modification of cytochrome P450 enzymes and membrane stability by dietary garlic powder may influence areas of GST-P positive foci and chemoprevention of post-initiation of rat hepatocarcinogenesis.